GB2495752A

GB2495752A - Gearbox with three planetary gear sets and a layshaft

Info

Publication number: GB2495752A
Application number: GB1118090.8A
Authority: GB
Inventors: Laurent Schlotter; Nicolas Alain Funalot
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-10-20
Filing date: 2011-10-20
Publication date: 2013-04-24
Also published as: GB201118090D0

Abstract

An eight-speed automatic gearbox comprises an input shaft 16, a layshaft 12 which is parallel to the input shaft 16, a first planetary gear set 13, a second planetary gear set 14 and a third planetary gear set 15 all of which are arranged concentrically to the input shaft 16. A planetary carrier 21 of the first planetary gear set 13 is connected to the input shaft 26, a ring gear 23 of the first planetary gear 13 set is connected to a sun gear 24 of the second planetary gear set 14 and a planetary carrier 32 of the second planetary gear set 14 is connected to a planetary carrier of the third planetary gear set 15. First, second and third clutches connect the input shaft 16, the ring gear 23 and a ring gear 33 to the layshaft 12 and a coupling clutch or a brake clutch connects a ring gear 33 of the third planetary gear set 15 to the layshaft 12. Planetary carrier 32 and the third planetary gear set 15 are connected to an output.

Description

Eight-speed automatic gear box Planetary gear trains, also known as epicyclic gear trains, are widely used in many auto- motive, aerospace and marine applications. In particular, planetary gear trains are fre-quently used in conventional autorriatic transmissions for passenger cars. In an automotive automatic transmission, the number of speed ratios is determined by the kinematic struc-ture and corresponding clutching sequence of its planetary gear train.

It is an object to provide an improved eight-gear gearbox which comprises planetary gear sets, for example with respect to spatial requirements.

To this end, the application discloses an eight-gear gearbox with an input shaft and a lay shaft which are arranged in parallel in a gearbox casing. The gearbox comprises a first planetary gear set, a second planetary gear set and a third planetary gear set which are arranged concentrically to the input shaft. According to the application, the gearbox pro-vides eight gears, which allow to use a combustion motor in an optimum range, especially a combustion motor with a narrow revolution to output torque characteristic. Moreover, if the gearbox is used in combination with an automatic shifting system, the large number of gears does not affect the usage comfort. By using the lay shaft, the number of planetary gear sets around the input shaft can be limited to three, even when as much as eight gears are provided. By limiting the number of planetary gear sets around a shaft, the length of the gear box can be reduced.

The planetary gear sets are connected such that a planetary carrier of the first planetary gear set is connected to the input shaft, a ring gear of the first planetary gear set is con-nected to a sun gear of the second planetary gear set and a planetary carrier of the second planetary gear set is connected to a planetary carrier of the third planetary gear set.

According to the application, clutches are provided to selectively direct the torque flow via the lay shaft. Specifically, a first clutch is provided between the lay shaft and the input shaft for selectively coupling the lay shaft to the input shaft. A second clutch is provided between the lay shaft and the ring gear of the first planetary gear set for selectively coupling the lay

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shaft to the ring gear. A third clutch is provided between the lay shaft and the ring gear of the second planetary gear set for selectively coupling the lay shaft to the ring gear of the second planetary gear set.

Furthermore, a coupling clutch is provided between the lay shaft and the ring gear of the third planetary gear set for selectively coupling the lay shaft to the ring gear of the third planetary gear set. Specifically, a coupling of the third planetary gear set to a lay shaft gear or outer gear, which rotates around the lay shaft, can be made such that an idler gear which is fixed to and corotating with a ring gear of the third planetary gear set engages into the lay shaft gear wheel.

According to the application, an output can be provided by connecting the planetary carrier of the second planetary gear set and the third planetary gear set to an output means, such as an output gear set and a differential.

According to the application, a torque flow via the lay shaft provides additional gears and thereby the lateral extension of the gearbox can be reduced. The clutches that are pro-vided between the input shaft and the lay shaft modify or turn off the torque flow via the lay shaft.

To further reduce the lateral size of the gearbox, the first planetary gear set and the second planetary gear set may be arranged essentially in the same gear plane. In this case, the sun gear of the second planetary gear set is designed as an outer gear which is arranged on an outer perimeter of the ring gear of the first planetary gear set.

In a further embodiment, the lay shaft is coupled to the third planetary gear set via a fourth planetary gear set. In this embodiment a coupling clutch is provided between the ring gear of the third planetary gear set and the lay shaft for selectively coupling the lay shaft to the ring gear via a fourth planetary gear set. This coupling clutch is designed as a brake clutch.

Furthermore, a fourth planetary gear set is provided, wherein a sun gear of the fourth planetary gear set is a fixed gear of the lay shaft and a ring gear of the fourth planetary gear set is enclosed by the coupling clutch. A lay shaft gear is connected to a planetary carrier of the fourth planetary gear set. The lay shaft gear engages in a gear wheel which is connected to the ring gear of the third planetary gear set.

In an alternative embodiment, the iay shaft is coupled to the third planetary gear set without the use of a fourth planetary gear set. This embodiment has fewer planetary gear sets and is more economical to build and maintain.

In this alternative embodiment, a coupling clutch is provided between the ring gear of the third planetary gear set for selectively coupling the ring gear of the third planetary gear set to the lay shaft via a gear wheel. Furthermore, the gear wheel is provided as a fixed gear wheel of the lay shaft, the gear wheel is enclosed by the coupling clutch and the gear wheel engages in another gear wheel which is connected to the ring gear of the third planetary gear set.

According to a more specific embodiment, the gearbox further comprises a hollow shaft for coupling the motion of the input shaft to the motion of the lay shaft. The hollow shaft is ar-ranged concentrically to the input shaft.

In more specific embodiments, the hollow shaft may comprise clutches, which are provided on an inner surface of the hollow shaft.

Firstly, the hollow shaft may comprise the first clutch and the first clutch may enclose a disk shaped portion of the planetary carrier of the first planetary gear set, The disk shaped por-tion is provided on the input shaft of the gearbox.

Secondly, the hollow shaft may comprise the second clutch, which encloses a clutch ring that is provided on a connecting portion which connects the ring gear of the first planetary gear set to the sun gear of the second planetary gear set.

Thirdly, the hollow shaft may comprise the third clutch, which encloses the ring gear of the second planetary gear set.

According to a further embodiment, the idler gear, which engages with the lay shaft gear, is provided on a hollow shaft which is supported on the input shaft.

In a further embodiment, the sun gear of the first planetary gear set is connected to a hol- low shaft, which is arranged concentrically around the input shaft. A crutch ring of the ho!-low shaft is enclosed by a brake clutch. Thereby, the sun gear of the first planetary gear set can be braked by engaging the brake clutch.

According to the application, an output means of the gearbox can be provided by connect-ing the planetary carrier of the second and the third planetary gear set to a differential via output gears, also known as an output gear set. In an especially compact design, the gear-box according to the application claims comprises a hollow output shaft for transmitting an output torque from the planetary carrier of the second planetary gear set and the third planetary gear set to a differential.

Therein, the hollow shaft is arranged concentrically to the abovementioned lay shaft and a first gear wheel of the hollow shaft engages into a gear ring that is provided on the plane-tary carrier of the second planetary gear set and the third planetary gear set. A second gear wheel on the hollow shaft engages into a gear wheel that is provided on a cage of a differential. According to the application a park wheel may be provided on the output hollow shaft. Thereby, the park wheel is placed close the differential with respect to the torque flow. A dog clutch or claw which is fixed to the gearbox casing can be brought in engage-ment with the park wheel to block the differential and hence the car wheels.

Specifically, the output gear set may comprise a ring gear, a first output gear and a second output gear, wherein the first and the second output gear are arranged around an axis and wherein the first output gear engages into the ring gear of the output gear set and the sec-ond output gear engages into a gear of the differential. The ring gear in turn engages into outer teeth of the planetary carrier of the second and the third planetary gear set.

Furthermore, the application discloses an automatic transmission with the abovementioned gearbox. The automatic transmission comprises a hydraulic actuation system wherein the clutches of the gearbox are connected to pistons of the hydraulic actuation system.

Furthermore, the application discloses a powertrain with the abovementioned gearbox ac-cording to one of the preceding claims. An output shaft of an engine is connected to the input shaft of the gearbox via transmission parts like flywheel, clutch, torque converter, chain, gear wheel etc. and the output means of the gearbox is connected to a wheel axle of a vehicle via further transmission parts like gear wheels shafts, differential, constant veloc-ity joints.

Moreover, the application discloses an automotive vehicle with the abovementioned power-train.

The subject of the application will now be explained in further detail with respect to the fol-lowing Figures in which Figure 1 illustrates a stick diagram of a first embodiment of a planetary gearbox, Figure 2 illustrates a stick diagram of a second embodiment of a planetary gearbox, Figure 3 illustrates a stick diagram of a third embodiment of a planetary gearbox, Figure 4 illustrates a stick diagram of a fourth embodiment of a planetary gearbox, Figure 5 illustrates a torque flow of a first gear, Figure 6 illustrates a torque flow of a second gear, Figure 7 illustrates a torque flow of a third gear, Figure 8 illustrates a torque flow of a fourth gear, Figure 9 illustrates a torque flow of a fifth gear, Figure 10 illustrates a torque flow of a sixth gear, Figure 11 illustrates a torque flow of a seventh gear, Figure 12 illustrates a torque flow of a eighth gear, Figure 13 illustrates a torque flow of a reverse gear, Figure 14 illustrates an output gearwheel arrangement of a gearbox according to the application, Figure 15 illustrates an output gearwheel arrangement of a gearbox according to the application, Figure 16 illustrates a schematic drawing of a vehicle with a gearbox according to the application.

In the following description, details are provided to describe the embodiments of the appli-cation, It shall be apparent to one skilled in the art, however, that the embodiments may be practised without such details.

Figure 1 shows a diagram of a planetary gearbox 10. The planetary gearbox 10 comprises first, second and third planetary gear sets 13, 14, 15 which are arranged around an input shaft 16 and a fourth planetary gear set 11 which is arranged around a lay shaft 12.

Clutches are denoted by the gears in which they are engaged, wherein the prefix "C" stands for a rotating clutch and the prefix "B" stands for a braking clutch. Portions of a sta- tionary gear box casing are symbolized by diagonal lines. For simplicity, the gear box cas-ing itself is not shown.

The input shaft 16 of the planetary gear box 10 is connected to an output shaft of an en-gine via transmission elements such as a flywheel or any other flexible connection part and, optionally, a clutch or a torque converter. The output shaft is connected to a differen-tial and to a wheel shaft via further transmission elements such as gear wheels, chains, transmission shafts, constant velocity joints etc. For simplicity, the transmission elements, the differential and the engine are not shown.

A sun gear 17 of the first planetary gear set 13 is provided on a hollow shaft 18 which partially encloses the input shaft 16. Planetary gears 19 of the first planetary gear set 13 are provided on shafts 21 of a planetary carrier 20. The shafts 21 are fixed on a disk shaped portion 22 of the planetary carrier 20 which is provided on the input shaft 16. A ring gear 23 of the first planetary gear set 13 is connected to a sun gear 24 of the second planetary gear set 14 via a connection part 25. The connection part 25 comprises a first cylinder 26, a disk shaped portion 27 and a second cylinder 28. A clutch ring 29 of a clutch C23468 is provided on the first cylinder 26.

Planetary gears 30 of the second planetary gear set 14 are provided on shafts 31 of a planetary carrier 32 which is at the same time a planetary carrier 32 of the third planetary gear set 15. A ring gear 33 of the second planetary gear set 14 engages with the planetary gears 30 of the second planetary gear set 14.

A sun gear 34 of the third planetary gear set 15 is provided on the hollow shaft 18.

Planetary gears 35 of the third planetary gear set 15 are supported on shafts of the plane-tary carrier 32. A ring gear 36 of the fourth planetary gear set 15 is fixed to an idler gear 37 which is supported on the hollow shaft 18.

The idler gear 37 engages to a lay shaft gear 38 which is supported on the lay shaft 12.

Shafts of a planetary carrier 39 of the fourth planetary gear set 11 are fixed on the lay shaft gear 38. The fourth planetary gear set 11 comprises a sun gear 40, which is provided on the lay shaft 12, planetary gears 41, which are supported on the shafts of the planetary carrier 39, and a ring gear 42. The ring gear 42 of the fourth planetary gear set 11 provides a clutch ring of a brake clutch B12345R. Clamping parts of the brake clutch 312345R, which are connected to a casing of the planetary gear box 10, enclose the ring gear 42.

A hollow shaft 43, which is arranged concentrically to the input shaft 16, comprises clamp- ing parts of a clutch Cl 3567, of a clutch C23468 and of a clutch C45678R which are pro-vided at an inner surface of the hollow shaft 34. The clamping elements of the clutches C13567, C23468 and C45678R enclose the disk shaped portion 22 of the planetary carrier 20, the clutch ring 29 and the ring gear 33, respectively. The hollow shaft 43 comprises an outer gear 44, which engages with a fixed gear 45 that is provided on the lay shaft 12.

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Furthermore, the hollow shaft 18, which is arranged concentrically to the input shaft 16 comprises a clutch disk 46 of a braking clutch B1278R. Clamping elements of the braking clutch B1278R, which are connected to the casing of the planetary gear box 10, enclose the clutch disk 46.

An output axis of the planetary gearbox 10, which is not shown in Fig. 1, is connected to the planetary carrier 32 of the second planetary gear set 14 and the third planetary gear set 15. An arrow 9 indicates the connection to the output axis.

Bearings may be provided for the planetary gears of the planetary gear sets 11, 13, 14, 15.

By way of example, a first bearing 50 of the first planetary gear set 13, a second bearing 51 of the second planetary gear set 14, a third bearing 52 of the third planetary gear set 15 and a fourth bearing 53 of the fourth planetary gear set are shown.

Furthermore, bearings or bushings are provided for the hollow shafts. By way of example, bearings 54, 55 of the hollow shaft 18, a bearing 56 of the idler gear 37, bearings 57, 58 of the connection part 25 and a bearing 59 of the lay shaft gear 38 are shown. The input shaft 16 and the lay shaft 12 are supported with bearings on a gearbox casing, which is not shown in Fig. 1.

For simplicity, the bearings are not shown in the torque flow diagrams of Fig. 5 to 13.

The planetary carriers may further comprise support structures, for example in ring shape or star shape, which link respective shafts 21, 31, 39 of the planetary carriers 31, 39 among each other or they can be shaped as cylinders onto which the shafts 21, 31, 39 of the planetary carriers are fixed.

The following table shows which of the clutches Cl 3567, C23468, C45678, B1278R, B12345R are engaged in which gear. By way of example, gear ratios and steps are shown as well. The symbol X in the cells of the table stands for an engagement of the respective clutch in the respective gear. The engagements are such that, from one gear to an adja-cent gear, one clutch is applied and one clutch is released. According to the application, a clutch engagement provides a frictional connection between two parts which results essen-tially in a fixed connection when the clutch is fully engaged.

B1278R B12345R C13567 C45678R 023468 Raflos Steps R -X X X -4M7 -0.84 1 X X 4S6 1.56 2X X X 3.12 1.55 3 X X X -2.02 1.24 4 X X X 1.62 1.30 X X X 1.25 1.25 6 X X 1.00.1.19 7 X X X 0.84 1.31 8 X X X -0.64 7.56 This table applies to the embodiments of Figs. ito 4. In the embodiments of Fig. 3 and 4, the clutch B1278R is a rotating clutch.

Fig. 2 shows a second embodiment of a planetary gearbox 10' which differs from the em- bodiment of Fig. 1 in that a second planetary gear set 14' is stacked on top of a first plane-tary gearset 13'. In the following, parts which are different from the gear box 10 of Fig. 1 are described.

A ring gear 23 of the first planetary gear set 13' comprises outer teeth which are the teeth of a sun gear 24 of the second planetary gear set 14'. A sun gear 24, planetary gears 30 and a ring gear 33 of the second planetary gear set 14' are arranged in essentially the same gear plane as a sun gear 17, planetary gears 19 and a ring gear 23 of the first plane-tary gear set 13'.

Furthermore, the ring gear 23 of the first planetary gear set 13' is connected to a clutch link 25'. The clutch link 25' comprises a cylindrical portion 26' and a disk shaped portion 29', The disk shaped portion 29' provides a clutch ring of the clutch C23465.

Similar to the embodiment of Fig. 1, a planetary carrier 32 of the second planetary gear set 14' is also the planetary carrier 32 of the third planetary gear set 15'. The relative dimen-sions of the gear wheels of Fig. 2 will in general be different from the relative dimensions shown in Fig. 1.

Fig. 3 shows an embodiment of a planetary gear box 10" which is similar to the planetary gear box 10 of Fig. 1 but in which the fourth planetary gear set 11 is replaced by an outer gear 38', a rotating clutch 612345R which is fixed to an inner perimeter of the outer gear 38' and a clutch disk 40' which is connected to the lay shaft 12. Clamping means of the rotating clutch B12345R enclose the clutch disk 40'.

Fig. 4 shows an embodiment of a planetary gear box 10" which is similar to the planetary gear box 10' of Fig. 2 but in which the fourth planetary gear 11 set is replaced by an outer gear 36', a rotating clutch B12345R which is fixed to an inner perimeter of the outer gear 38' and a clutch disk 40' which is connected to the lay shaft 12. Clamping means of the rotating clutch 812345R enclose the clutch disk 40'.

The relative dimensions of the gear wheels of the embodiment of Figs. 3 and 4 can be made such that essentially the same transmission ratios as in Figs. 1 and 2 are provided.

As compared to the embodiments of Figs. 1 and 2, the number of parts and the lateral size is further reduced. The embodiments of Fig. I and 2 already provide a reduction of the lateral size of a planetary gearbox by using an arrangement in which the planetary gear sets are distributed over two shafts rather than being arranged in one line. The reduction of the lateral size of a planetary gearbox according to the application is particularly advanta-geous in front wheel drives in which the gear box is mounted transversally in the vehicle.

The torque flows of the gears will now be explained with respect to Fig. 5 to 13 which show the torque flows for the embodiment of Fig. 1 The torque flow for the embodiment of Fig. 2 is similar to the torque flow for the embodiment of Fig. 1. Parts of the stacked first and sec-ond planetary gear sets 13' and 14' in Figs. 2 and 4 correspond to parts of the adjacent first and second planetary gear sets 13 and 14 in Figs. 1 and 3. The connecting part 25 of Figs. 1 and 3 corresponds to the ring shaped portion which connects the ring gear 23 of the first planetary gear set 13 in Figs. 2 and 4, and the sun gear 24 of the second planetary gear set 14 and the first cylinder 26 in Figs. 1 and 3 corresponds to a first cylinder 26' in Figs. 2 and 4. The clutch ring 29 of Figs. I and 3 corresponds to a ring shaped part 29' of Figs. 2 and 4.

The torque flow for the embodiments of Figs. 3 and 4 differs froni the torque flow of Figs. 1 and 2 in that a torque flow from the lay shaft 12 via the fourth planetary gear set 11 to the lay shaft gear 38 is replaced by a torque flow from the lay shaft 12 via the fixed gear 40', the rotating clutch B12345R and the outer gear 38', which corresponds to the lay shaft gear 38 of the embodiments of Figs. 1 and 2.

Fig. 5 shows a torque flow of the first gear in which a torque from the input shaft 16 is transmitted via the disk shaped portion 22, the clutch C13S67, the hollow shaft 43, the outer gear 44, the fixed gear 45, the lay shaft 12, the sun gear 40, the planetary gears 41 and the planetary carrier 39 of the fourth planetary gear set 11, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the planetary carrier 32 of the third planetary gear set 15 to the output shaft. The engagement of the clutch 81 2345R causes the planetary gears 41 of the fourth planetary gear set 11 to roll off on the fixed ring gear 42. The engagement of the clutch BI 278R in the first gear causes the planetary gears of the third planetary gear set 15 to roll off on the fixed sun gear 34 of the third planetary gear set 15.

Fig. 6 shows a torque flow of the second gear in which a torque from the input shaft 16 is 23 transmitted via the disk shaped portion 22, the planetary carrier 21, the planetary gears 19 and the ring gear 23 of the first planetary gear set 13, the first cylinder 26 of the connection part 25, the clutch ring 29, the clutch C23468, the hollow shaft 43, the outer gear 44, the fixed gear 45, the lay shaft 12, the ring gear 40, the planetary gears 41 and the planetary carrier 39 of the fourth planetary gear 11, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the planetary carrier 32 of the third planetary gear set to the output shaft. The engagement of the clutch 81278R causes the planetary gears 19 of the first planetary gear set 13 to roll off on the fixed sun gear 17 and the planetary gears 35 of the second planetary gear set 14 to roll off on the fixed sun gear 34. The en-gagementofthe clutch B12345R causes the planetary gears 41 of the fourth planetary gear set to roll off on the fixed ring gear 42.

Fig. 7 shows a torque flow of the third gear in which, a torque from the input shaft 16 is transmitted via the disk shaped part 22, the clutch C13567, the hollow shaft 43, the outer gear 44, the fixed gear 45, the lay shaft 12, the sun gear 40, the planetary gears 41, the planetary carrier 39, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the planetary carrier 32 of the third planetary gear set 15 to the output shaft.

In the third gear, the engagement of the clutch B12345R causes the planetary gears 41 to roll off on the fixed ring gear 42 of the fourth pLanetary gear set 11. The engagement of the clutches 013567 and 023468 causes the first planetary gear set to act as a rigid part and the sun gear 34 of the third planetary gear set 15 to rotate with the speed of the input shaft 16.

In the fourth, sixth and eighth gears, the simultaneous engagement of the clutches 023468 and C45678R causes the second planetary gear set 14 to act as a rigid part, which in turn causes the planetary carrier 32 of the second planetary gear set 14 to rotate with the same speed as the ring gear 23 of the first planetary gear set 13.

Fig. S shows a torque flow of the fourth gear in which, the torque from the input shaft 16 is transmitted via the disk shaped part 22 to the planetary shafts 21 and the planetary gears 19 of the first planetary gear set 13. Then, the torque flow splits up into a first and a second torque path. The first torque path comprises a torque flow via the ring gear 23 of the first planetary gear set 13, the clutch 023468, the hollow shaft 43, the clutch C4S678R, the ring gear 33, the planetary gears 30 and the planetary carrier 32 of the second planetary gear set 14 to the output shaft.

The second torque path of the fourth gear comprises a torque flow via the clutch 023468, the hollow shaft 43, the outer gear 44, the fixed gear 45, the lay shaft 12, the sun gear 40, the planetary gears 41 and the planetary carrier 39 of the fourth planetary gear set 11, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the plane-tary carrier 32 of the third planetary gear set 15 to the output shaft.

Fig. 9 shows a torque flow of the fifth gear in which a torque is transmitted from the input shaft 16 via the disk shaped portion 22, the clutch 013567, the hollow shaft 43 to the clutch C45678R. At the cLutch C45678R the torque flow splits up into a first and a second torque path. The first torque path comprises a torque flow via the outer gear 44, the fixed gear 45, the lay shaft 12, the sun gear 40, the planetary gears 41 and the planetary carrier 39 of the fourth planetary gear set 11, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the planetary carrier 32. The second torque flow path comprises a torque flow via the ring gear 33, the planetary gears 30 and the sun gear 24 of the second planetary gear set 14, the connection part 25, the ring gear 23, the planetary gears 19 and the sun gear 17 of the first planetary gear set 13, the sun gear 34, the planetary gears 35 and the planetary carrier 32 of the third planetary gear set.

Fig. 10 shows a torque flow of the sixth gear in which a torque from the input shaft 16 is transmitted via the disk shaped portion 22, the clutch C13567, the hollow shaft 43, the clutch C45678R, the ring gear 33, the planetary gears 30, the planetary carrier 32 to the output shaft.

In the sixth gear, the engagement of the clutches 013567 and C23468 causes the sun gear 24 of the second planetary gear set 14 to rotate with the speed of the input shaft 16.

The engagement of the clutch C13567 and C45676R causes the ring gear 33 of the sec- ond planetary gear set 14 to rotate with the speed of the input shaft 16. Thereby, the plane-tary carrier 32 of the second planetary gear set 14 rotates with the speed of the input shaft 16. :15

Fig. 11 shows a torque flow of the seventh gear in which a torque from the input shaft 16 is transmitted via the disk shaped portion 22, the shafts 21, the planetary gears 19 and the ring gear 23 of the first planetary gear set 13, the connection part 25, the sun gear 24, the planetary gears 30 and the planetary carrier 32 of the second planetary gear set 14. In the seventh gear, the engagement of the clutch B1278R causes the planetary gears 19 of the first planetary gear set 13 to roll off on the fixed sun gear 17 of the first planetary gear set 13. In the seventh gear, the engagement of the clutches C13567 and C45676R causes the ring gear 33 of the second planetary gear set 14 to rotate with the speed of the input shaft 16.

Fig. 12 shows a torque flow of the eighth gear in which a torque from the input shaft 16 is transmitted via the disk shaped part 22, the shafts 21, the planetary gears 19, the ring gear 23, the clutch 023468, the hollow shaft 43, the clutch C45678R, the ring gear 33 and the planetary gears 30 and the planetary carrier 32 of the second planetary gear set 14 to the output shaft.

In the eighth gear, the engagement of the clutches C23468 and C45678 causes the sec-ond planetary gear set 14 to act as a rigid part which rotates with the rotation speed of ring gear 23 of the first planetary gear set 13. The engagement of the clutch 81278R causes the planetary gears 19 of the first planetary gear 13 to roll off on the fixed sun gear 17.

Fig-13 shows a torque flow of the reverse gear in which a torque flow from the input shaft iBis transmitted via the disk shaped portion 22, the shafts 21, the planetary gears 19, the outer ring 23 of the first planetary gear set 13! the connection part 25, the sun gear 24, the planetary gears 30 and the ring gear 9 of the second planetary gear set 14, the clutch C45676R, the fixed gear 45, the lay shaft 12, the sun gear 40, the planetary gears 41 and the planetary shaft 39 of the fourth planetary gear set 11, the lay shaft gear 38, the idler gear 37, the ring gear 36, the planetary gears 35 and the planetary carrier 32 of the third planetary gear set to the output shaft.

The engagement of the clutch 61278R causes the planetary gears 19 of the first planetary gear set l3to roll off on the fixed sun gear 17 of the first planetary gear set 13. The en-gagement of the clutch B12345R causes the planetary gears 41 of the fourth planetary gear set 11 to roll off on the fixed ring gear 42 of the fourth planetary gear set 11.

Figure 14 shows an arrangement of gearwheels for transmitting the output torque of the planetary carrier 32 of the second planetary gear set 14 and of the third planetary gear set to a gear wheel 50 of a differential, which is not shown in Fig. 14.

An output gear ring 47 is provided on the planetary carrier 47, which meshes with a first gearwheel that is provided on a hollow output shaft 65. The hollow output shaft 65 is sup-ported on the Ia shaft 12 by bearings 63 and 64. On one end of the hollow output shaft 65, a second gearwheel is provided which meshes with a gear wheel 50 that is provided on the cage of a differential, which is not shown here.

On the other end of the hollow output shaft 65, a park gear 60 is provided which can be fixed to the casing of the gearbox by a claw that is not shown. The Lay shaft 12 is supported on the gearbox casing by bearing 61 and 62.

Arrows 9 indicates schematically an output torque flow. The torque is transmitted from the planetary carrier 32 via the output gearwheel 37, the first gear wheel 48, the hollow output shaft 65 and the second gear wheel 49 to an outer gear wheel 50 of the cage of the differ-ential.

By way of example, the arrangement of gearwheels is shown for the embodiments of Figs. 1 and 2. Fig. 14 applies to the embodiments of Figs. 3 and 4 as well. In this case, the gear wheels 40' and 38' are provided on the lay shaft 12 instead of the gear wheel 40 and the fourth planetary gear set 11. This situation is shown in Fig. 15.

In an alternative embodiment, which is similar to Figs. 14 and 15, the output torque is not directed via a hollow output shaft 65 but via a separate lay shaft, Thereby, friction can be reduced. However, the embodiments of Fig. 14 and Fig. 15 result in a more compact gear-box layout.

Fig. 16 shows a schematic view of a car with a gearbox according to the preceding em- bodiments. A crankshaft of a motor 66 is connected to a torque converter which is con-nected to the input shaft 16 of the gearbox 68 with gearbox casing 69. The outer gear wheel 50 is provided on the differential 70. Left and right halves of a wheel shaft 71 are connected to bevel gearwheels of the differential 70. Wheels 72 are provided on the outer ends of the wheel shaft 71. For simplicity, the internal structure of the gearbox 68, which is according to one of the abovementioned embodiments, is not shown in detail in Fig. 16.

Although the above description contains much specificity, these should not be construed as limiting the scope of the embodiments but merely providing illustration of the foreseeable embodiments. Especially the above stated advantages of the embodiments should not be construed as limiting the scope of the embodiments but merely to explain possible achievements if the described embodiments are put into practise. Thus, the scope of the embodiments should be determined by the claims and their equivalents, rather than by the

examples given.

Claims

<claim-text>CLAIMSGearbox (10, 10', 10", 10") comprising -an input shaft (16) and a lay shaft (12) which are arranged in parallel in a gear-box casing, -a first planetary gear set (13, 13'), a second planetary gear set (14, 14') and a third planetary gear set (15, 15') which are arranged concentrically to the input shaft (16), wherein a planetary carrier (21) of the first planetary gear set (13, 13') is connected to the input shaft (16), a ring gear (23) of the first planetary gear set (1 3, 13') is con- nectedto a sun gear (24) of the second planetary gear set (14, 14'), a planetary car-rier (32) of the second planetary gear set (14, 14') is connected to a planetary carrier (32) of the third planetary gear set (15, 15') and wherein -a first clutch (C13567) is provided between the lay shaft (12) and the input shaft (16), -a second clutch (C23468) is provided between the lay shaft and the ring gear (23) of the first planetary gear set (13, 13'), -a third clutch (C45678R) is provided between the lay shaft (12) and the ring gear (33) of the second planetary gear set (14, 14'), -a coupling clutch (812345R) is provided between the lay shaft (12) and the ring gear (36) of the third planetary gear set (15, 15'), and wherein the planetary carrier (32) of the second planetary gear set (14) and the third planetary gear set (15)is connected to an output means.</claim-text> <claim-text>2. Gearbox (10', 10") according to claim 1, wherein the first planetary gear set (13') and the second planetary gear set (14') are arranged essentially in the same gear plane.</claim-text> <claim-text>3. Gearbox (10, 10') according to one of the preceding claims, wherein a coupling clutch (812345R) is provided between the ring gear (36) of the third planetary gear set and the lay shaft (12), the coupling clutch being designed as brake clutch, and wherein furthermore a fourth planetary gear set (11) is provided, a sun gear (40) of the fourth planetary gear set (11) being a fixed gear of the lay shaft (12), a ring gear (42) of the fourth planetary gear set (11) being enclosed by the coupling clutch (B12345R), wherein a lay shaft gear (38)is connected to a planetary carrier (39) of the fourth planetary gear set (11) and wherein the lay shaft gear (38) engages in a gear wheel (37) which is connected to the ring gear (36) of the third planetary gear set (15).</claim-text> <claim-text>4. Gearbox (10", 10") according to one of the claims Ito 2, wherein a coupling clutch (B12345) is provided between the ring gear (35) of the third planetary gear set (15), wherein further a gear wheel (40) is provided, the gear wheel (40) being a fixed gear wheel of the lay shaft (12) and the gearwheel (40') being enclosed by the coupling clutch (B12345R), wherein the gear wheel (40') engages in a gear wheel (37) which is connected to the ring gear (36) of the third planetary gear set (15).</claim-text> <claim-text>5. Gearbox (10, 10', 10", 10") according to one of the preceding claims, further com-prising a hollow shaft (43) for coupling the motion of the input shaft to the motion of the lay shaft (12), the hollow shaft (43) being arranged concentrically to the input shaft (16) 6. Gearbox (10, 10', 10", 10") according to claim 5, wherein the hollow shaft (43) com- prises the first clutch (013567) the first clutch (013567) enclosing a disk shaped por-tion (20) of the planetary carrier (20) of the first planetary gear set (13, 13'), the disk shaped portion (20) being provided on the input shaft (16) of the gearbox (10, 10', 10", 10").7. Gearbox (10, 10', 10", 10") according to claim 5, wherein the hollow shaft (43) com-prises the second clutch (023466) which encloses a clutch ring (29), the clutch ring (29) being provided on a connecting portion (26) which connects the ring gear (23) of the first planetary gear set (13, 13') to the sun gear (24) of the second planetary gear set (14, 14').8. Gearbox (10, 10', 10", 10") according to claim 5 or claim 6, wherein the hollow shaft (43) comprises the third clutch (C45676R) which encloses the ring gear (33) of the second planetary gear set (14, 14').9. Gearbox (10, 10', 10", 10") according to one of the preceding claims, wherein the idler gear (37)is provided on a hollow shaft which is supported on the input shaft (16).10. Gearbox (10, 10', 10111 10) according to one of the preceding claims, wherein the sun gear (1 7) of the first planetary gear set (11) is connected to a hollow shaft (18), the hollow shaft (18) being arranged concentrically around the input shaft (16) and wherein a clutch ring (46) of the hollow shaft (18) is enclosed by a brake clutch (81 278R).11. Gearbox (10, 10', 10, 10") according to one of the preceding claims, wherein the planetary carrier of the second and the third planetary gear set is connected to a dif-ferential via an output gear set.12. Gearbox (10, 10', 10", 10") according to cLaim 11, wherein the output gear set com-prises a ring gear, a first ouput gear and a second output gear, wherein the first and the second output gear are arranged around an axis and wherein the first output gear engages into the ring gear of the output gear set and the second output gear en-gages into a gear (50) of the differential.13. Gearbox (10, 10', 10", 10") according to one of the previous claims, the gearbox comprising a hollow output shaft (65) for transmitting an output torque from the planetary carrier (32) of the second planetary gear set (14, 14') and the third plane- tary gear set (15, 15') to a differential (70), wherein the hollow output shaft (65) is ar-ranged concentrically to the lay shaft (12) and wherein a first gear wheel (48) of the hollow output shaft (65) engages into a gear ring (47) that is provided on the plane-tary carrier (32) of the second planetary gear set (14, 14') and the third planetary gear set (15, 15').14. Powertrain with a gearbox (10, tO', 10", 10") according to one of the preceding claims wherein an output shaft of an engine (66) is connected to the input shaft (16) of the gearbox (10, 10', 10", 10") and wherein the output means of the gearbox (10, 10', 10", 10") is connected to a wheel shaft (71) of a vehicle.15. Automotive vehicle comprising a powertrain according to claim 14.</claim-text>